T6. Less often than others

Given a non-empty string composed solely of letters from the Latin alphabet, identify the letter that occurs the least frequently. Treat uppercase and lowercase letters as equivalent. If there is a tie, select the letter that appears later in the alphabet. Present your answer in uppercase.

Constraints

The input string's length will not exceed 100 characters.

Input Format

The input consists of a single line containing the string.

Output Format

Output a single line with the solution to the problem.

Examples